You want to find the ratios that are equivalent to 24:10 or 72:30 (those two are equal). It's a ratio of 2.4:1. 12:5 when simplified also gives you 2.4:1 so that's correct, and 288:120 will get you the same. To check like I did, divide both sides of the ratio by the number on the right, and if you get 2.4:1 then it's equivalent.
